The present invention relates generally to a drive, and more particularly to a drive utilizing an energy-storing means. Still more particularly the present invention relates to a spring drive which is especially suited for mobile toys.
Spring drives used for mobile toys and similar purposes generally employ a spiral spring whose inner end is connected with a rotary shaft and whose outer end is connected with the output shaft of the drive via a transmission. A key is provided which engages with the spring shaft and turns the latter, thereby tensioning the spring and storing energy in the same. In such construction the transmission and the outer end of the spring must be arrested to prevent immediate dissipation of the energy input at the spring shaft.
This type of construction is very widely used, and in many instances is entirely satisfactory. However, it has been found that small and very small children are incapable of winding such spring drives by means of the key provided, sometimes because they do not understand the reasons for the use of the key, sometimes because they have inadequate strength or coordination to use the key. It has been observed that such children frequently attempt to wind the spring not by means of the key, but by turning the spring shaft itself or even the output shaft of the drive. In any case, the keys in such spring drives are usually components which are discrete from the remainder of the drive and which are quite often lost, at which point it is impossible to further utilize the drive except in the unlikely event that the user should have or be able to obtain a key which can replace the one that has been lost.
An additional drawback of the these prior-art devices is the fact that the transmission which is interposed between the spring and output shaft makes the winding of the spring relatively time-consuming and tiring for a small child, aside from the fact that there exists the danger that turning of the key in the wrong direction --it is well known that there is only one direction in which the key must be turned to wind the spring-- the spring may be damaged, a danger which also exists from possible over-tightening of the spring.
Attempts have been made to overcome these difficulties. Thus, spring drives are known from the art in which the spring is tensioned by means of a friction wheel connected with the spring shaft and which rotates the spring shaft when the toy or other element in which the spring drive is incorporated, is pressed down so that the friction wheel contacts a surface on which the toy is then moved along to turn the friction wheel and thereby wind the spring. Other embodiments of the prior art prefer to utilize auxiliary gears which are placed in mesh with the spring shaft and the output shaft when the toy is pressed down onto a surface and is then moved along the surface.
However, in these as in all other well-known spring drives which avoid the use of a key for winding the spring, the output shaft must be turned only in one predetermined direction for tensioning the spring, so that the spring is tensioned only if the toy vehicle or the like is moved over a support surface in a given direction. This is disadvantageous because it presupposes that a playing child understands that the spring can be tensioned only by moving the toy in this one direction, a degree of perception which is absent in small children who, it has been observed, invariably attempt to wind the spring by moving the toy not only in one direction but back and forth in mutually opposite directions.